"All Carb" is the total amount of dietary carbohydrate in your intake.

"Net Carb" is the TOTAL minus indigestible FIBER. Some people also subtract some (or all) of sugar-alcohol grams for their total. I do not, and leave all sugar alcohols in my total as they all cause an increase in my own blood glucose levels.

That being said, fiber amounts listed on 'low-carb' product labels can be misleading. Any product that advertises as "low net carbs" or "low active carbs", etc., may be listing fiber that CAN be digested, or may NOT be adding sugar alcohols into the carb total.

For sugar alcohols (maltitol, sorbitol, etc.) - as a rule of thumb - many subtract 1/2 the amount instead of all of it. This is what's recommended by some diabetic organizations. IE: a product with 20g of carbohydrate but 12g of sugar alcohols would calculate to 14g net carb ... (the 20 total minus 6 - half the sugar alcohols)

With fruit, veggies, etc., you can be pretty sure of net-carb amounts. But not so with packaged products...

Some examples:

1 cup broccoli: 6g carb, 2g fiber = 4g net carbs
1 cup raspberres: 15g carb, 8g fiber = 7g net carbs

By comparison:

Atkins Strawberry Almond Bar: 20g carb, 5g fiber, 12g sugar alcohols = ~9g net carbs (although Atkins subtracts all sugar alcohols, and 'claims' 3 net grams - which is misleading as sugar alcohols do convert to glucose.)

Quest Chocolate PB Bar: 25g carb, 17g fiber (claimed, but not likely), 5g sugar alcohols. Quest claims these are 3g 'Active' carbs ... yet they spike virtually every diabetic tested as-if they've eaten a full 20-25g of carbohydrate. As such their fiber claim is dubious. It may be 'fiber' but it's NOT indigestible.

So like I said, watch product labels or you're likely getting much more carbohydrate, and as-such, glucose - into your system than you think.